Lakes overflow, turn spotlight on drain management
Commuters driving through Manyata Tech Park were in for a surprise on Wednesday morning – many roads were flooded, and at Chikkabanavara, a road had turned into a rivulet and people stood on the middle of the road trying to catch fish.
The heavy rains that lashed the city late on Tuesday and early Wednesday resulted in the filling up of many lakes and overflow from the waste weirs, causing flood water to enter homes, damaging white goods and vehicles.
Vidyaranyapura lake (also known as Narasipura lake), Chikkabanavara lake, Singapura lake, Puttenahalli lake, Nagawara lake, Rachenahalli lake, Hebbala lake, Jakkur lake, Yelahanka lake, Sheelavanthakere, Sadaramangala lake were some that have overflowed.
Stating that this was a common phenomenon following heavy rainfall, civic activist V. Ramaprasad, co-founder of Friends of Lake, said when a lake overflows through the waste weirs, local communities usually perform a small prayer called ‘Kodi Pooje’.
“It is a good sign that the lakes are overflowing. Hopefully, the lakes have been rejuvenated to ensure that the original holding capacity of the water bodies are maintained. Any rejuvenation should take into account the original holding capacity while the Detailed Project Report is being drafted,” he said.
Rainwater expert S. Vishwanath said that the lakes are not designed to be flood management structures. While faulting the rajakaluve designs, he said with bunds being created on all sides of lakes, the sheet flow was not getting into the lake, causing it to accumulate and flood surrounding areas.
G.S. Srinivas Reddy, former director of Karnataka State Natural Disaster Monitoring Centre (KSNDMC), stressed on the need to properly assess the carrying capacity of the stormwater drain network in the city. He said common reasons for flooding could be siltation of drains, encroachment and increase in the quantity of runoff.
B.S. Prahlad, BBMP’s chief engineer (stormwater drains), claimed the carrying capacity of drains was around 50 mm. He said the city had received nearly 140 mm of rains in the span of a few hours. He claimed that regular maintenance of drains had been taken up across the city and that encroachments were being cleared as and when they were identified.
More rain expected over next 4 days
Citizens have to brace themselves, as heavy rains are expected to lash the city over the next four days.
C.S. Patil, Director (Weather Forecast), Indian Meteorological Department, Bengaluru said with the presence of three systems, monsoon was vigorous over south interior Karnataka and active over north interior Karnataka.
The present synoptic conditions are an offshore trough from the Maharashtra coast to north Kerala, a circulation over the Arabian Sea, off the Karnataka coast, and an east-west shear zone over peninsular India.